Disc apparatus having a plurality of reading/recording head driving manners for disc track seeking movement

ABSTRACT

A head reads information from and/or records information to a disc. A head driving unit drives the head on a disc in substantially radial direction thereof, the moving being executed in either a first driving manner or a second driving manner different from the first driving manner and the moving of the head effecting seeking of a track formed on the disc. A disc loading detecting unit detects loading of a disc in said disc apparatus. A switching unit switches over a driving manner from one to another among the first and second driving manners, wherein the switching unit selects the first driving manner while a disc is loaded in the disc apparatus and the switching unit selects the second driving manner while a disc is not the in the disc apparatus.

This is a division of application Ser. No. 08/110620 filed Aug. 20,1993, Pat. No. 5,521,770.

BACKGROUND OF THE INVENTION

The present invention relates to a disc apparatus, in particular,relates to a disc apparatus for reading information from and/orrecording information to a recording medium such as a flexible magneticdisc.

A construction of one example of flexible magnetic disc apparatus (suchapparatus will be referred to as simply "magnetic disc apparatus"hereinafter) will now be described with reference to FIGS.1 and 2.

A flexible magnetic disc (this disc will be referred to as simply "disc"hereinafter) 3 is, as known, enclosed in an enclosing case 4. In FIGS.1and 2, the magnetic disc apparatus 1 has a holder 5 located above aframe 2 thereof. The enclosing case 4 (this case is indicated with chainlines in the figures) will be inserted into the holder 5.

The magnetic disc apparatus 1 has a construction by which, with theknown art, the holder 5 will operate as follows. The holder will belowered, in FIG. 2, in response to the enclosing case 5 being insertedinto the magnetic disc apparatus 1. Conversely, the enclosing case 4will be ejected as a result of the holder 5 being raised. The movementsindicated by the terms "lowering" and "raising" are with respect to thedirections in FIG. 2, hereinafter.

The magnetic disc apparatus 1 has a known mechanism by which magneticheads 10 and 12 access the disc 3 in response to the movement of theholder 5. The movement of the holder 5 is the holder 5 being lowered.Conversely, by this mechanism, the magnetic heads 10 and 12 go away fromthe disc 3 in response to the movement of the holder 5. The movement ofthe holder 5 is the holder 5 being raised.

The holder 5 has a top plate 5a located on the top thereof. An opening5b is provided in the top plate 5a into which a below-described magnetichead unit 8 is inserted.

The magnetic head unit 8 has the above-mentioned magnetic heads 10 and12 which are used to read information from and/or to record informationto an information track in the disc 3. A shutter lever 6, having aL-letter like shape, is provided on the top plate 5a. This shutter lever6 effects opening a shutter (not shown in the figures) provided for onthe enclosing case 4 in response to the enclosing case 4 being insertedinto the magnetic disc apparatus 1.

This shutter lever 6 is pivotably supported on the top plate 5a. Theshutter provided on the enclosing case 4 has the following knownfeatures. The shutter effects protecting the disc 3. This shutter has tobe opened so as to make the opening on the enclosing case 4. Thus,through the made opening, the magnetic heads 10 and 12 may access thedisc 3 enclosed in the enclosing case 4. This accessing by means of themagnetic heads 10 and 12 enables them to read information from and/or torecord information to an information track formed on the disc 3.

The shutter lever 6 is always biased, in the clockwise direction in FIG.1, by means of a coil spring 7 with its pulling force. This biasing inthe clockwise direction results in closing, by means of the shutterlever 6, the shutter of the enclosing case 4 when the enclosing case 4is inserted into the holder 5. An engaging pin 6a projects from the topof the shutter lever 6. This projection of the engaging pin 6a isdirected toward into the inside of the holder 5 through an opening 5chaving an arc shape. This direction corresponds to that toward thereverse side of the sheet on which FIG. 1 is represented. This engagingpin 6a engages the shutter of the enclosing case 4 so as to open theshutter.

The above-mentioned magnetic head unit 8 has the following construction.The magnetic head unit 8 comprises a carriage 9 which slidably moves inthe directions A and B shown in FIG. 1. As shown in FIG.2, the lowermagnetic head 10 is mounted on the top surface near the left end of thecarriage 9. An arm 11 is up-and-down swingably supported on the rightend post 9a of the carriage 9. The upper magnetic head 12 is mounted onthe bottom surface of the left end of the arm 11.

The carriage 9 engages with a lead screw (not shown in the figures)which is driven by a stepper motor (not shown in the figures). With thisengagement, the carriage may be moved in either the directions A or B inresponse to the turning of the lead screw. This movement of the carriage9 enables the magnetic heads 10 and 12 moving on the disc 3 in itsradial directions.

The arm 11 is biased in the direction C shown in FIG. 2 by means of atorsion spring 9c, shown in FIG. 1, with its pressing force. Thistorsion spring 9c is mounted on the post 9a of the carriage 9. Anabutting bar 11a projects from the left side of the arm 11 as shown inFIG. 1. This abutting bar 11a abuts-on the top plate 5a of the holder 5.In this construction, when the enclosing case 4 is to be ejected fromthe magnetic disc apparatus 1 (the state of the magnetic head apparatus1 in which the enclosing case 4 has been ejected will be referred to as"disc unloading state" hereinafter), the magnetic disc apparatus 1operates as follows.

Then, as mentioned above, the holder 5 is raised and the enclosing caseis thus ejected. The arm 11 is raised upward in FIG. 2 as a result ofbeing pushed by means of the raised holder 5. This pushing the arm 11 iseffected through the abutting bar 11a. That is, the top plate 5a of theholder 5 pushes the abutting bar 11a so as to raise the arm 11. Thus,the arm 11 is raised against the reverse-direction pushing force appliedby means of the torsion spring 9c. As a result, the upper magnetic head12 is raised. Thus, the upper magnetic head 12 goes away from the lowermagnetic head 10.

The state of the magnetic disc apparatus 1 in which the enclosing case 4is loaded in the apparatus 1 as a result of the enclosing case 4 havingbeen inserted therein will be referred to as "disc loading state"hereinafter.

When the magnetic disc apparatus 1 moves from the disc unloading stateto the disc loading state thereof, the holder 5 is lowered as mentionedabove. Thus, the top plate 5a is lowered. As a result, the effect havingbeen performed on the abutting bar 11a by means of the top plate 5a isreleased accordingly. This effect is to maintain the abutting bar 11a atthe raised position thereof. Thus, the arm 11 is lowered by means of thetorsion spring 9c with its pushing force. Thus, the upper magnetic head12 is lowered.

Thus, the upper magnetic head 12 approaches the lower magnetic head 10.As a results, both the upper and lower magnetic heads 10 and 12 togethersandwich the disc 3.

Generally speaking, a magnetic disc apparatus for recording informationto and/of reading information from a flexible magnetic disc has thefollowing features. In such a magnetic disc apparatus, for example, inthe magnetic disc apparatus 1 as mentioned above, the magnetic disc 1 isa recording medium which may be changed by another similar disc. Thatis, the disc 3 loaded in the magnetic disc apparatus 1 may be replacedby another disc as occasion demands. That is, the disc 3 may be ejectedso as to be unloaded from and another disc may be inserted so as to beloaded into the magnetic apparatus 1.

Generally speaking, such a magnetic disc apparatus, for example, themagnetic disc apparatus 1, even in the disc unloading state, may operateas follows. The magnetic disc apparatus 1 executes seeking actionaccording to a corresponding command provided from a host apparatus or amother apparatus thereof. This seeking action is performed by moving theheads 10 and 12 in the directions which would correspond to radialdirections of a disc if the disc were loaded therein. The host apparatusor the mother apparatus comprises for example, a computer utilizing themagnetic disc apparatus 1 as means for recording and/or readinginformation associated with the computer.

Further, actions executed in a such a magnetic disc apparatus will bereferred to as "head loading/unloading action" or "headloading/unloading movement" These actions are respectively those thatthe heads, in the example, the heads 10 and 12 approach/go away fromeach other, in directions substantially perpendicular to the informationrecording surface of the disc 3.

A reason of such seeking action being to be executed even during thedisc unloading state will now be described. By moving the heads 10 and12 prior to the disc 3 being loaded in the magnetic disc apparatus 1, itis possible to generate a condition at a moment the disc 3 is loaded.The condition to be generated is a preparation for a process to beperformed on the disc 3 and the condition is that the heads 10 and 12are on the so-called #00 tracks formed on the disc 3. Such generating ofa condition as a preparation for a process to be performed on a disc is,in other word, initializing of the heads. Such initialization of theheads being executed before the disc is loaded in the magnetic discapparatus enables the host apparatus to execute the process of using themagnetic disc apparatus with the disc without any delay time or idlingtime.

Such seeking action being executed in its disc unloading state needs thefollowing operation in the magnetic disc apparatus 1. As mentionedabove, the upper magnetic head 12 is raised when the disc 3 is beingejected. For this purpose, the abutting bar 11a of the arm 11 is pushedupward by means of the top plate 5a of the holder 5. Thus, thiscondition is maintained during its disc unloading state. That is, inthis condition, the abutting bar 11a is pushed upward by means of thetop plate 5a.

The above-mentioned seeking action by the heads 10 and 13, which are theparts of the magnetic head unit 8, has to be executed in this condition.Thus, the magnetic head unit 8 has to move in this condition. That is,the abutting bar 11a, which is the part of the magnetic head unit 8 asmentioned above, has to slide on the top plate 5a which pushes theabutting bar 11a. As a result, considerable friction occurs between theabutting bar 11a and the top plate 5a during this seeking action. Thefriction force in this friction occurring corresponds to the pushingforce resulting from the pushing of the abutting bar 11a by means of thetop plate 5a.

This pushing of the abutting bar 11a by means of the top plate 5a isexecuted in the disc unloading state but is not executed in the discloading state. Thus, an extra force is needed to execute the seekingaction in the disc unloading state in comparison to that in the discloading state. To provide this extra force, the stepper motor needsextra capacity in driving the magnetic head unit 8. This extra capacityin the stepper motor is not needed in the seeking action in the discloading state. This extra capacity in the stepper motor may generallyraise an electric power consumption amount in driving the stepper motorand may raise a noise level in this driving, unnecessarily.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a disc apparatus inwhich power consumption and noise involved in its seeking action in itsdisc loading state may be reduced.

To achieve the object of the present invention, a disc apparatusaccording to the present invention comprises:

at least one head for reading information from and/or recordinginformation to a disc;

head driving means for driving said head on a disc in a substantiallyradial direction thereof, the moving being executed in either a firstdriving manner or a second driving manner different from said firstdriving manner and the moving of said head effecting seeking a trackformed on the disc;

disc loading detecting means for detecting loading of a disc in saiddisc apparatus; and

switching means for switching over a driving manner from one to anotheramong said first and second driving manners, wherein said switchingmeans selects said first driving manner while a disc is loaded in saiddisc apparatus and said switching means selects said second drivingmanner while a disc is not loaded in said disc apparatus.

In this construction, it is possible to switch over the driving mannerso as to reduce the driving force by means of the head driving means tobe an appropriate amount in its disc loading state. Thus, it is possibleto reduce amounts of power consumption and noise to be appropriate onesaccordingly in the disc loading state.

Other objects and further features of the present invention will becomemore apparent from the following detailed description when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows schematic plan construction view of the example of amagnetic disc apparatus and a magnetic disc apparatus according to firstto third embodiments of the present invention;

FIG. 2 shows schematic side sectional view of the apparatus shown inFIG. 1;

FIG. 3A shows schematic block diagram of part of the magnetic discapparatus according to the first embodiment, relevant to the presentinvention, in its disc loading state;

FIG. 3B shows schematic block diagram of part of the magnetic discapparatus according to the first embodiment, relevant to the presentinvention, in its disc unloading state;

FIG. 4 shows schematic block diagram of part of the magnetic discapparatus according to the second embodiment, relevant to the presentinvention;

FIG. 5 shows schematic circuit diagram of part of a driver control unitin the magnetic disc apparatus according to the second embodiment,relevant to the present invention;

FIG. 6 shows schematic circuit diagram of part of the magnetic discapparatus according to the third embodiment, relevant to the presentinvention; and

FIGS. 7A-7J show signal-wave-form time charts associated with theapparatus shown in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A magnetic disc apparatus 100 according to the first embodiment of thepresent invention will now be generally described with reference toFIGS. 3A and 3B.

The general mechanical construction of the magnetic disc apparatus issubstantially the same as that of the example of the magnetic discapparatus 1 described above with reference to FIGS.1 and 2. Thus, such adescription will be omitted.

This magnetic disc apparatus 100 comprises a disc detection unit 135, aswitching unit 137, a stepper driver 142, and a stepper motor 143. Thestepper motor 143 effects to drive the magnetic heads and 12 so as tobring the heads 10 and 12 to desired information tracks formed on thedisc 3. This driving of the magnetic heads 10 and 12 corresponds to theabove-mentioned seeking action.

The stepper driver 142 effects control of this function effected bymeans of the stepper motor 143. The switching unit 137 effects switchingover a driving manner from one to another among a predeterminedplurality of driving manners. In this embodiment, the predeterminedplurality of driving manners comprise two different driving manners: thefirst driving manner and the second driving manner. In either the firstdriving manner or the second driving manner, the stepper driver 142controls the seeking action performed by means of the stepper motor 143.

The disc detection unit 135 effects determining whether or not anenclosing case 4 enclosing a disc 3 is loaded in the magnetic discapparatus 100. The open/close switch 135 in FIGS. 3A and 3B closes inthe disc loading state and opens in the disc unloading state.

The switching unit 137 may switch over the driving manner in response tothe change in the state between the disc loading state and the discunloading state, as the result of the detection performed by means ofthe disc detection unit 135.

An operation performed in the magnetic disc apparatus 100 will now bedescribed.

When the enclosing case 4 is inserted in to the magnetic disc apparatus100 so that the disc 3 is loaded in the apparatus 100, the apparatus 100operates as follows. As shown in FIG. 3A, the disc detection unit 135detects the enclosing case 4 has been inserted. Thus, the switch 135 inFIG. 3A closes. As a result, the switching unit 137 switches over thedriving manner so as to select the first driving manner.

This first driving manner comprises a reduced power driving mode. Inthis reduced power driving mode, the stepper driver 142 controls thestepper motor 143 so as to cause the motor 143 to drive the magnetichead unit 8 having heads 10 and 12 with a predetermined reduced drivingpower.

When the enclosing case 4 is ejected from the magnetic disc apparatus100 so that the disc 3 is unloaded from the apparatus 100, the apparatus100 operates as follows. As shown in FIG. 3B, the disc detection unit135 detects the enclosing case 4 has been ejected. Thus, the switch 135in FIG. 3A opens. As a result, the switching unit 137 switches over thedriving manner so as to select the second driving manner.

This second driving manner comprises a full power driving mode. In thisfull power driving mode, the stepper driver 142 controls the steppermotor 143 so as to cause the motor 143 to drive the magnetic head unit 8having heads 10 and 12 with a full driving power without any reductionof the driving power.

Thus, in the magnetic disc apparatus 100, the driving force with whichthe stepper motor 143 drives the magnetic head unit 8 is reduced in thedisc loading state. Thus, unnecessary excessive driving force may beprevented from being applied to the magnetic head unit 8 in the discloading state. Thus, the power consumption and the noise is reducedaccordingly in the disc loading state.

The magnetic disc apparatus 200 according to the present invention willnow be described with reference to FIG. 4.

The general mechanical construction of the magnetic disc apparatus 200is substantially the same as that of the example of the magnetic discapparatus 1 described above with reference to FIGS.1 and 2. Thus, such adescription will be omitted.

A motor-on signal which has been provided from the host apparatus may beinput at a terminal 30. In this case, a driver unit 31 causes a spindlemotor 32 to run. As a result, a magnetic disc 3 is turned by means ofthe spindle motor 32. In this condition, the magnetic head 12 may readinformation from and/or record information to the magnetic disc 3.

A read/write unit 33 supports the reading/recording performed throughthe magnetic head 12. The read/write unit 33 is connected with the hostapparatus through a read/write terminal 34. (Actually, the read/writeterminal comprises a read terminal and a write terminal separately.)

A mechanical switch 35 effects detecting whether or not an enclosingcase 4 is loaded in the magnetic disc 200. When the enclosing case 4 isloaded in the apparatus 200, the mechanical switch 35 operatesaccordingly. This operation of the mechanical switch 35 results inopening of a switch SW linked with the mechanical switch 35. As aresult, a disc-in sensor signal having a logical H level is generated.

Conversely, when the enclosing case 4 is ejected from the apparatus 200,the mechanical switch 35 operates accordingly. This operation of themechanical switch 35 results in closing of the switch SW. As a result, adisc-in sensor signal having a logical L level is generated.

Both the H and L level signals are provided to the disc changegenerating unit 38.

The following signals are respectively provided to the a driver controlunit 37 from the host apparatus through terminals 39-41. These signalscomprise a drive select signal, a direction signal and a step signal.The drive select signal indicates that the user selects this magneticdisc apparatus 200 from among a plurality of similar informationrecording means belonging to the common host apparatus. As a result ofreceiving the drive select signal, the magnetic disc apparatus 200enters in its condition where the host apparatus may control themagnetic disc apparatus 200.

The direction signal indicates a direction for the seeking movement,that is, a direction in which the magnetic heads move and the directionsignal indicates either the outward direction of the radial directionsof the disc 3 or the inward direction of the radial directions of thedisc 3. The step signal indicates that the host apparatus intends themagnetic disc apparatus 200 to execute a seeking action such asmentioned above. In this seeking action, the magnetic head 12 moves onthe disc 3 so as to seek a desired information track formed on the disc3. The step signal may comprise one pulse so as to move the head 12located on the disc 3 by a width corresponding to one track formed onthe disc 3.

The driver control unit 37 generates, in accordance with the three kindsof signal and the above-mentioned disc-in sensor signal, a drivingsignal for causing the stepper motor 43 to run.

A driver unit 42 provides, in accordance with the driving signalprovided by the driver control unit 37, driving electric current to thestepper motor 43. This driving electric current directly drives thestepper motor 43.

The running of the stepper motor 43 effects to move the magnetic head 12in the radial direction of the disc 3. That is, the seeking action isexecuted.

The disc change generating unit 38 outputs a predetermined disc changesignal as a result of receiving the above-mentioned disc-in sensorsignal, as follows. Since the state was changed from the disc loadingstate to the disc unloading state, the disc generating unit 38 keepsoutputting a first predetermined disc change signal to the hostapparatus through a terminal 44.

In this condition, that is, in the disc unloading state, the disc-insensor signal has a logical L level as mentioned above. When the hostapparatus receives this first predetermined disc change signal, the hostapparatus recognizes that the enclosing case 4 is not loaded in themagnetic disc apparatus 200.

Then, after the enclosing case 4 has been loaded in the magnetic discapparatus 200, the following operation is executed. The logical levelassociated with the disc-in sensor signal becomes a logical H levelaccordingly as mentioned above. The disc change generating unit 38 thenoutputs a second predetermined disc change signal by the followingsteps. First the unit 38 receives the disc-in sensor signal which hasbecome the logical H level as mentioned above. Second the unit 38receives the step signal through the terminal 41.

The host apparatus recognizes, by receiving the second predetermineddisc change signal, that the enclosing case 4 is loaded in the magneticdisc apparatus 200.

Part of the above-mentioned driver control unit 37 will now be describedwith reference to FIG. 5.

In FIG. 5, a power-reduction pulse generating unit 50 generates a pulsesignal. This pulse signal effects to substantially reduce, in the discloading state, the driving power with which the stepper motor 43 drivesthe head 12. That is, for example, a duty ratio in this pulse signal maybe 50%.

The term "duty ratio" means a percentage of the entire time, duringwhich the signal level is H. Thus, the duty ratio of 50% means thatfirst time while the signal level is H and second time while the signallevel is L alternate periodically where the first time has the sameinterval as that of the second time.

The driving force with which the stepper motor 43 drives the head 12 iseither applied or cut off in response to either the level H or the levelL of the pulse signal generated by the power-reduction pulse generatingunit 50. That is, the generated signal having the level H results in thepredetermined driving force being applied to the head 12 and the level Lresults in no driving force being applied thereto.

As a result of averaging the effect during the period of the level H andthe effect in the other period of the level L, this condition issubstantially equivalent to that in which the half of the predetermineddriving force is always applied to the head 12. This is because, in the50% duty ratio, the interval while the predetermined force is appliedand the other interval while no force is applied are the same.

Further, in the disc unloading state, the predetermined driving force isalways applied to the head 12 by means of the stepper motor 43.

By the above-mentioned function, the driving force to be applied to thehead 12 by means of the stepper motor 43 may be controlled as follows.The driving force is selected to become the predetermined force in thedisc unloaded state and the driving force is selected to become adriving force resulting from desirably reducing the predetermined force.The percentage of the reduced driving force in the predetermined forcemay be desirably selected by changing the duty ratio in the pulse signalgenerated by the power-reduction pulse generating unit 50.

This power-reduction pulse generating unit 50 has, for example, thefollowing composition. A disc apparatus such as the magnetic discapparatus 200 includes an internal-clock-signal generating mechanism forgenerating an internal clock signal to be used for known processesexecuted in the disc apparatus.

Such an internal clock signal may be utilized for generating the pulsesignal to be generated by the power-reduction pulse generating unit 50.That is, frequency dividing may be performed on clock pulses associatedwith the internal clock signal. As a result of the frequency division,for example, a pulse signal having its pulse period of 40μs, that is,having its pulse frequency of 25kHz may be obtained. This pulsefrequency corresponds to non-audio frequency. Thus, this obtained pulsesignal may be provided, as the above-mentioned pulse signal to begenerated by the power-reduction pulse generating unit 50, to a logicalAND device 51.

As shown in FIG. 5, not only such a pulse signal but also the disc-insensor signal, input through a terminal 35T, are provided to the logicalAND device 51. Output provided from the logical AND device 51 is thenprovided to a logical OR device 53. Further, a signal resulting frominverting the disc-in sensor signal by means of an inverter 52 is alsoprovided to the logical OR device 53. Output provided from the logicalOR device 53 is then provided to the logical NAND device 54 togetherwith a stepper drive enable signal.

This stepper drive enable signal is an internal signal in the magneticdisc apparatus 200. This stepper drive enable signal is generated in thedriver control unit 37 in another part not shown in FIG. 5. Thisgeneration of the stepper drive enable signal is executed in accordancewith the above-mentioned drive select signal and step signal.

This stepper drive enable signal has a logical level H where thefollowing two conditions are simultaneously fulfilled. The firstcondition is that the drive select signal indicates the magnetic discapparatus 200 is selected. The second condition is that the step signalindicates the seeking action to be executed. (It should be noted thatsuch a step signal which initiates the generating of the step driveenable signal comprises an internal step signal and an external stepsignal. The external step signal is provided, for example, from the hostcomputer and the internal step signal is formed based on the externalsignal by such a device as an internal step generation unit 61 shown inFIG. 6 to be described below. This is because, the host computer merelyprovides one pulse as the external step signal to make the head move byone track on the disc while the disc apparatus needs two pulses to causethe head to move by one track. Thus, one additional pulse is provided asthe internal step signal for each pulse provided as the external stepsignal so as to provide two pulses to cause the head to move by onetrack.) The logical level H in the stepper drive enable signal thusmeans the host apparatus intends the magnetic disc apparatus 200 toperform a certain seeking action.

An operation executed in the composition shown in FIG. 5 will now bedescribed.

In the disc unloading state, the disc-in sensor signal has a logical Lsignal as mentioned above. This disc-in sensor signal is inverted in itslogical level by means of the inverter 52 so that logical level in thedisc-in sensor signal becomes H. Then, the logical OR device 53 providesa logical H level signal irrespective of a signal provided by thelogical AND device 51.

In this condition, the logical NAND device 54 provides a logical L levelsignal while the stepper drive enable signal having a logical H level isprovided. In this case, a transistor Q₁ in a driver unit 42 turns on.This turn-on condition in the transistor Q₁ is maintained withoutregarding the pulse signal provided from the power-reduction pulsegenerating unit 50. This is because the logical AND device 51 effectsclosing the gate function thereof as a result of the logical L level inthe disc-in sensor signal provided thereto. Thus, a predetermineddriving electric current is constantly supplied to the stepper motor 43by means of the turning-on transistor Q₁ via a terminal 56. Thus, thestepper motor 43 drives the magnetic head 12 with the correspondingconstant predetermined driving force.

In the disc loading state, the disc-in sensor signal has a logical Hlevel as mentioned above. Thus, the L level signal, resulting frominverting this H level signal by means of the inverter 52, is providedto the input terminal of the logical OR device 53. Then, output providedfrom the logical OR device 53 becomes identical to that provided fromthe logical AND device 51. That is, the gate function of the logical ORdevice 53 opens for passing the output provided from the logical ANDdevice 51 therethrough.

Further, the logical H level of the disc-in sensor is provided to thelogical AND device 51. Thus, output provided by the logical AND device51 becomes identical to that provided by the power-reduction pulsegenerating unit 50. Thus, the gate function of the logical AND device 51opens for passing the output provided from the unit 50 therethrough.

Thus, the pulse signal provided by the power-reduction pulse generatingunit 50 passes through the logical AND device 51 and then passes throughthe logical OR device 53. In this condition, output provided from thelogical NAND device 54 becomes a signal having a logical level resultingfrom inverting the output provided by the logical OR device 53 while thestepper drive enable signal has a logical H level.

That is, the output provided from the logical NAND device 54 becomes asignal resulting from inverting, in its level, the pulse signal providedby the power-reduction pulse generating unit 50. Thus, a state in thetransistor Q₁ receiving this output provided by the logical NAND device54 is different between its turning on state and its turning off statein response to the difference of logical level of this pulse signalbetween L and H.

Thus, the transistor Q₁ alternates allowing and not allowingperiodically the predetermined driving current being supplied to thestepper motor 43 via the terminal 56 accordingly. Thus, the steppermotor 43 drives the magnetic head 12 with the periodically alternateddriving power between the predetermined force and zero force (no power).Thus, the stepper motor 43 substantially drives the head 12 with aconstant driving power having an amount resulting from reducing thepredetermined power in a rate corresponding to the duty ratio in thepulse signal provided by the power-reduction pulse generating unit 50.

By adjusting the duty ratio in the pulse signal, an appropriate amountof, that is, not an unnecessarily great amount of the driving force maybe applied to the head 12 even in the disc loading state. Thus, thepower consumption and the noise may be reduced accordingly.

In the circuit construction shown in FIG. 5, it may be preferable toprovide smoothing means so as to eliminate undesirable effects caused bythe pulse signal being used for driving the stepper motor 43. Thisundesirable effects may comprise audio noise and/or electrical noiseoccurring as a result of the violently alternated change in runningconditions of the stepper motor.

For this purpose, a smoothing capacitor may be inserted between theterminal 56 and the ground. As a result, the pulse like driving currentprovided to the stepper motor 43 is smoothed. Thus, the followingpossibilities may be eliminated. A possibility of occurrence of suchaudio noise may be eliminated and a possibility of interference causedby such electrical noise may be eliminated. This influence may affectother apparatus associated with magnetic disc apparatus 200. Thus,reliability of the magnetic disc apparatus 200 may be improved.

The magnetic disc apparatus 300 according to the third embodiment of thepresent invention will now be described with reference to FIG. 6.

The general mechanical construction of the magnetic disc apparatus 300is substantially the same as that of the example of the magnetic discapparatus 1 described above with reference to FIGS.1 and 2. Thus, such adescription will be omitted.

The magnetic disc apparatus 300 has a driver control unit 37, a driverunit 42 and a stepper motor 43.

In FIG. 6, a drive select signal DS and a step signal EXTSTEP arerespectively provided, via terminals 39 and 41, to a logical AND device60. These drive select signal DS and step signal EXTSTEP respectivelyact similarly to the drive select signal and step signal described withreference to FIG. 4.

The step signal EXTSTEP may pass through the logical AND device 60 onlywhile the drive select signal DS having a logical H level is provided tothe logical AND device 60. This passing through step signal EXTSTEP isthen provided to an internal step generation unit 61, a step intervalsupervisory unit 62 and a logical OR device 63 respectively. FIGS.7A and7D respectively show wave forms X(DS) and X(EXTSTEP). These wave formsX(DS) and X(EXTSTEP) are respectively obtained by respectively invertingthe wave form of drive select signal DS and the wave form of the stepsignal EXTSTEP.

(However, these inverted signals X(DS) and X(EXTSTEP) are not shown tobe used in FIG. 6. For example, in FIG. 6, these inverted signals X(DS)and X(EXTSTEP) may be again inverted prior to input at the terminals 41and 39. Generally speaking, such inverted signals are frequently used insuch a magnetic disc apparatus. FIG. 6 illustrates a signal flow as oneexample according to the third embodiment of the present invention.Thus, a person skilled in the art may easily modify the compositionshown in FIG. 6 so as to make a composition according to the thirdembodiment of the present invention which composition directly uses suchinverted signals X(EXTSTEP) and X(DS). )

Further, a direction signal DIR shown in FIG. 7B is provided, via aterminal 40, to the internal step generation unit 61. This directionsignal DIR acts similarly to that described with reference to FIG. 4.

The stepper motor 43 has to turn, in response to the step signal EXTSTEPprovided to the driver control unit 37, as follows. The stepper motor 43drives the magnetic heads 10 and 12 so as to perform a seeking actionsuch as mentioned above. In this seeking action, the magnetic heads 10and 12 respectively move on the information recording surface of thedisc 3 by a width corresponding to one information track in response toone step pulses of the step signal EXTSTEP being provided. (As shown inFIG. 7D, an interval between such two step pulses is a time t1.)

To make the stepper motor 43 achieve such a seeking action by means ofthe magnetic heads 10 and 12, the internal step generation unit 61operates as follows. The unit 61 generates a substep signal SUBSTEPwhich is obtained by delaying by a time t2 the step signal EXTSTEPpassing through the logical AND device 60. This substep signal SUBSTEPhas a wave form shown in FIG. 7E.

The step signal EXTSTEP passing through the logical AND device 60 andthe substep signal SUBSTEP are respectively provided to the logical ORdevice The logical OR device 63 then provides an output signal to asignal-phase mask time generation unit 64 and a 2-2 phase energizegeneration unit 65. This output signal has been obtained as a result ofthe logical device 63 performing the logical OR function on the inputsignals EXTSTEP and SUBSTEP therein.

The step interval supervisory unit 62 controls the internal stepgeneration unit 61 in response to the time interval t1 between steppulses associated with the step signal EXTSTEP. As a result, the unit 61appropriately generates the step pulses associated with the step signalEXTSTEP.

Further, the step interval supervisory unit 62 controls the single-phasemask time generation unit 64. Thus, the signal-phase mask timegeneration unit 64 generates a mask signal in an appropriate timing.This mask signal is used for masking below-mentioned switching signalsappropriately. In this mask signal, the signal level is a logical Hlevel during a time the switching signals is to be masked.

A gate function is performed on this mask signal through a logical ANDdevice 67. That is, while a disc-in sensor signal has a logical H level,that is, in a disc loading state such as mentioned above,the mask signalmay pass through the logical AND device 67. The disc-in sensor signal isshown in FIG. 7C and is provided via a terminal 35T. This passingthrough mask signal is then provided to the 2-2 phase energizegeneration unit 65.

The 2-2 phase energize generation unit 65 effects generating switchingsignals ΦA, ΦB, Φ*A, 101 *B respectively shown in FIGS.7F-7I. FIG. 7F-7Ishow signal wave forms in a case where the magnetic heads 10 and 12 arerespectively to perform a seeking action in a step-in condition in whichthe heads 10 and 12 respectively moves inward on the disc 3.

There may be another case where the magnetic heads 10 and 12 arerespectively to perform a seeking action in a step-out condition inwhich the heads 10 and 12 respectively moves outward on the disc 3. Inthis other case, in the disc loading state, below-described steps are tobe executed backwardly to a sequence of steps S1-S8 (the term "step"will be omitted so that, for example, a "step S1" will be replaced bysimply "S1", hereinafter), that is, a sequence of steps in the othercase is to be as follows: S8, then S7, then S8, then S5, then S4, thenS3, then S2 and then S1. Similarly, in this other case, in the discunloading state, a sequence of steps is to be S7^(a) then S5^(a) thenS3^(a) and then S1^(a). (This sequence in steps is the reverse of that,that is S1^(a) then S3^(a), then S5^(a) and then S7^(a) (even though thestep S7^(a) is not shown in FIG. 7J) in the disc loading state as shownin FIG. 7J.)

The 2-2 phase energize generation unit 65 operates, in accordance withthe provided signals, that is, the output from the logical OR device 63and the direction signal DIR, as mentioned below. Further, the 2-2 phaseenergize generation unit 65 appropriately masks the above four kinds ofswitching signals ΦA, ΦB, Φ*A, Φ*B respectively. Time corresponding toS1-S8 shown in FIG. 7F-7I show the results obtained by such masking.

The mask signal provided by the logical AND device 67 has a logical Hlevel for each time interval of time intervals t3, t4, t5 and t6. Duringthese time intervals the following masking function is performed. Duringthe time interval t3 (S2), the switching signal Φ*B becomes a logical Llevel as a result of the masking function. During this time interval t3,the switching signal Φ*B should be a logical level H if the maskingfunction was not performed.

During the time interval t4 (S4), the switching signal Φ*A becomes alogical L level as a result of the masking function. During this timeinterval t4, the switching signal Φ*A should be a logical level H if themasking function was not performed.

During the time interval t5 (S6), the switching signal ΦB becomes alogical L level as a result of the masking function. During this timeinterval t5, the switching signal ΦB should be a logical level H if themasking function was not performed.

During the time interval t6 (S8), the switching signal ΦA becomes alogical L level as a result of the masking function. During this timeinterval t6, the switching signal ΦA should be a logical level H if themasking function was not performed.

FIG. 7J shows a name of a switching signal which is in a logical in eachstep.

The four kinds of switching signals ΦA , ΦB, Φ*A, Φ*B are respectivelyprovided to field effect transistors (they will be referred to as "FETs"hereinafter) in a driver unit 42 as shown in FIG. 6.

The switching signal ΦA is provided to the gates of P-channel FET P1 andN-channel FET N1 respectively. The switching signal ΦB is provided tothe gates of P-channel FET P2 and N-channel FET N2 respectively. Theswitching signal Φ*A is provided to the gates of P-channel FET P3 andN-channel FET N3 respectively. The switching signal Φ*B is provided tothe gates of P-channel FET P4 and N-channel FET N4 respectively.

The sources of the FETs P1-P4 are respectively connected with the powersource V_(DD). The sources of the FETs N1-N4 are respectively grounded.

The drains of the FETs P1 and N1 are respectively connected with one endof a coil A of the stepper motor 43 while the drains of the FETs P3 andN3 are respectively connected with the other end of a coil A of thestepper motor 43. The drains of the FETs P2 and N2 are respectivelyconnected with one end of a coil B of the stepper motor 43 while thedrains of the FETs P4 and N4 are respectively connected with the otherend of a coil B of the stepper motor 43.

In this connection, the FETs P1 and N3 respectively turn on while theswitching signal ΦA is in a logical L level and the switching signal Φ*Ais in a logical H level. As a result, a driving current flows from theFET P1 to FET N3 through the coil A. That is, in FIG. 6, a drivingcurrent flows in the coil A in a direction D2.

By such an operation as mentioned above, the stepper motor 43 having theknown construction with the coils A and B is driven with the knowndriving mechanism.

The FETs N1 and P3 respectively turn on while the switching signal ΦAare in a logical H level and the switching signal Φ*A is in a logical Llevel. As a result, a driving current flows from the FET P3 to FET N1through the coil A. That is, in FIG. 6, a driving current flows in thecoil A in a direction D1.

By such an operation, the stepper motor 43 is driven.

The FETs P2 and N4 respectively turn on while the switching signal ΦBare in a logical L level and the switching signal Φ*B is in a logical Hlevel. As a result, a driving current flows from the FET P2 to FET N4through the coil B. That is, in FIG. 6, a driving current flows in thecoil B in a direction D2.

By such an operation, the stepper motor 43 is driven.

The FETs N2 and P4 respectively turn on while the switching signal ΦBare in a logical H level and the switching signal Φ*B is in a logical Llevel. As a result, a driving current flows from the FET N2 to FET P4through the coil B. That is, in FIG. 6, a driving current flows in thecoil B in a direction D1.

By such an operation, the stepper motor 43 is driven.

As mentioned above, the above-mentioned masking signal is not providedin the disc unloading state as a result of the gate function of thelogical AND device 67. Thus, in the disc unloading state, the followingswitching signals are provided by the 2-2 phase energize generating unit65.

That is, in these switching signals, while the magnetic heads 10 and 12respectively move on the disc 3 by a width corresponding to two tracks,switching signals having logical H levels may change as follows: (ΦA,ΦB) (S1), then (ΦA,Φ*B) (S3), then (Φ*A, Φ*B) (S5), then (Φ*A,ΦB) (S7),and then (ΦA , ΦB) (S1^(a)). As mentioned above, in the step-outcondition, the above sequence is to be reversed so that ( ΦA , ΦB) (S1),then (Φ*A,ΦB) (S7), then (Φ*A, Φ*B) (S5), then (ΦA,Φ*B) (S3), and then(ΦA, ΦB) (S1^(a)).

(Here, the above mentioned cycle for the magnetic heads 10 and 12respectively moving on the disc 3 by a width corresponding to twotracks, is not limited to result from one rotation of the stepper motor43. This cycle may result from 1/3 rotation of the stepper motor 43 ormay result from 1/4 rotation thereof.)

On the other hand, in the disc loading state, in the switching signals,while the magnetic heads 10 and 12 respectively move on the disc 3 by awidth corresponding to two tracks, switching signals having logical Hlevels may change, as a result of a corresponding masking function suchas mentioned above, as follows as shown in FIG. 7J: (ΦA, ΦB) (S1), then(ΦA) (S2), then (ΦA, Φ*B) (S3), then (ΦB) (S4), then (Φ*A, Φ*B) (S5),then (Φ*A) (S6), then (Φ*A,ΦB) (S7), then (ΦB) (S8), and then (ΦA,ΦB)(S1^(a)).

Here, by the masking function, A back part of (ΦA, ΦB) (S1) has beenmasked so as to make (ΦA)(S2); a back part of (ΦA , Φ*B) (S3) has beenmasked so as to make (Φ*B)(S4); a back part of (ΦA, Φ*B) (S5) has beenmasked so as to make (Φ*A)(S6); and a back part of (Φ*A, ΦB) (S7) hasbeen masked so as to make (ΦB)(S8).

As mentioned above, in the step-out condition, the above sequence is tobe reversed so that (ΦA, ΦB) (S1), then (ΦB) (S8), then (Φ*A,ΦB) (S7),then (Φ*A) (S6), then (Φ*A, Φ*B) (S5), then (ΦB) (S4), then (ΦA ,Φ*B)(S3), then (ΦA) (S2), and then (ΦA,ΦB) (S1^(a)).

By such masking function, by which the back part of each step may bechanged as mentioned above, driving of the stepper motor 43 may becomerelatively smoothed in the disc loading state. This driving of thestepper motor 43 is executed by step pulses associated with the stepsignal EXTSTEP being provided to the drive control unit 37.

Further, by such masking function, the power consumption used in thisdriving and the noise occurring in this driving may be reduced in thedisc loading state.

This is because, the manners of change of logical levels of theswitching signals, occurring when one step pulse of the step signalEXTSTEP has been provided to the drive control unit 37, are differentbetween the disc unloading state and the disc loading state. That is, inthe disc loading state, 4 times the change in logical levels of theswitching signals are executed while in the disc unloading state onlytwice the change is executed.

In the example shown in FIG. 7J, in the disc unloading state, twice, S3and S5 of the change are executed while in the disc loading state, 4times, S2, S3, S4 and S5 are executed.

As mentioned above, with the disc apparatus according to the presentinvention, power saving and noise reduction may be achieved in the discloading state. Thus, such a disc apparatus may be very useful forpractical uses.

The present invention is not limited to such a magnetic disc apparatus.The present invention may be applied to other kinds of disc apparatus,such as including optical disc apparatuses and magneto-optical discapparatuses.

Further, the present invention is not limited to the above describedembodiments, and variations and modifications may be made withoutdeparting from the scope of the present invention.

What is claimed is:
 1. A disc apparatus comprising:at least one head forreading information from and/or recording information to a disc; headdriving means for driving said head on a disc in substantially radialdirection thereof, the moving being executed in either a first drivingmanner or a second driving manner different from said first drivingmanner and the moving of said head effecting seeking a track formed onthe disc; disc loading detecting means for detecting loading of a discin said disc apparatus; and switching means for switching between saidfirst and second driving manners, wherein said switching means selectssaid first driving manner while a disc is loaded in said disc apparatusand said switching means selects said second driving manner while a discis not loaded in said disc apparatus wherein said head driving meanscomprises a stepper motor having a first coil and a second coil whichcoils generate magnetic fields of substantially different phases; andwherein said stepper motor drive said head as a result of said first andsecond coils being energized in a first energizing manner while saidfirst driving manner is applied and said stepper motor drives said headas a result of said first and second coils being energized in a secondenergizing manner while said second driving manner is applied; andwherein a double-phase energizing period and a single-phase energizingperiod alternate periodically in said first energizing manner, and saiddouble energizing period is maintained in said second energizing manner;and wherein both said first and second coils are energized in saiddouble-phase energizing period and either said first coil or said secondcoil is energized in said single-phase energizing period.
 2. The discapparatus according to claim 1, wherein:said first energizing mannercomprises at least one cycle comprising steps of: a double-phaseenergizing step (S1) in which both said first and second coils areenergized in a first polarity; then a single-phase energizing step (S2)in which said first coil is energized in said first polarity and saidsecond coil is not energized; then a double-phase energizing step (S3)in which said first coil is energized in said first polarity and saidsecond coil is energized in a second polarity different from said firstpolarity; then a single-phase energizing step (S4) in which said firstcoil is not energized and said second coil is energized in said secondpolarity; then a double-phase energizing step (S5) in which both saidfirst and second coils are energized in said second polarity; then asingle-phase energizing step (S6) in which said first coil is energizedin said second polarity and said second coil is not energized; then adouble-phase energizing step (S7) in which both said first is energizedin said second polarity and second coil is energized in said firstpolarity; and then a single-phase energizing step (S8) in which saidfirst coil is not energized and said second coil is energized in saidfirst polarity; said second energizing manner comprises at least onecycle comprising steps of: a double-phase energizing step (S1) in whichboth said first and second coils are energized in a first polarity; thena double-phase energizing step (S3) in which said first coil isenergized in said first polarity and said second coil is energized in asecond polarity different from said first polarity; then a double-phaseenergizing step (S5) in which both said first and second coils areenergized in said second polarity; and then a double-phase energizingstep (S7) in which both said first coil is energized in said secondpolarity and second coil is energized in said first polarity.
 3. Thedisc apparatus according to claim 1, wherein:said first energizingmanner comprises at least one cycle comprising steps of: a single-phaseenergizing step (S8) in which said first coil is not energized and saidsecond coil is energized in said first polarity; then a double-phaseenergizing step (S7) in which both said first coil is energized in saidsecond polarity and said second coil is energized in said firstpolarity; and then a single-phase energizing step (S6) in which saidfirst coil is energized in said second polarity and said second coil isnot energized; then a double-phase energizing step (S5) in which bothsaid first and second coils are energized in said second polarity; thena single-phase energizing step (S4) in which said first coil is notenergized and said second coil is energized in said second polarity;then a double-phase energizing step (S3) in which said first coil isenergized in said first polarity and said second coil is energized in asecond polarity different from said first polarity; then a single-phaseenergizing step (S2) in which said first coil is energized in said firstpolarity and said second coil is not energized; and then a double-phaseenergizing step (S1) in which both said first and second coils areenergized in a first polarity; said second energizing manner comprisesat least one cycle comprising steps of:a double-phase energizing step(S7) in which both said first coil is energized in said second polarityand said second coil is energized in said first polarity; then adouble-phase energizing step (S5) in which both said first and secondcoils are energized in said second polarity; and then a double-phaseenergizing step (S3) in which said first coil is energized in said firstpolarity and said second coil is energized in a second polaritydifferent from said first polarity; and a double-phase energizing step(S1) in which both said first and second coils are energized in a firstpolarity.
 4. The disc apparatus according to claim 1, wherein said headdriving means comprises a servomotor which turns in a predeterminedangle in response to each step pulse being applied thereto; andwhereinthe turning of said servomotor in said predetermined angle comprisesfirst plurality of intermittent angles of sub-turning, said firstplurality of intermittent angles of sub-turning being obtained as aresult of dividing said predetermined angle by a first number while saidfirst driving manner is applied, and the turning of said servomotor insaid predetermined angle comprises second plurality of intermittentangles of sub-turning, said second plurality of intermittent angles ofsub-turning being obtained as a result of dividing said predeterminedangle by a second number different from said first number while saidfirst driving manner is applied.